Drilling tool and detachable bit



Dec. 3', 1929. E. s. MECULLOUGH ET AL 1,733,332

DRILLING TOOL AND DETACHABLE BIT Filed Feb. 12, 1929 'Inventor Z13 'z /Jimu z/ 154/ B. Swazi/('7 Attorney Patented Dec. 3, 1929 UNITED STATES PATENT OFFICE ELZADORE S. MCCULLOUGH AND ASA B. SMITH, OF FAIRMONT, WEST VIRGINIA I DRILLIKG TOOL AND DETACHABLIE BIT Application filed February 12, 1929. Serial No. 339,411.

This invention relates to improvements in drills, and 'more particularly. to a combination drill tool and detachable bit.

In combination, drilling tools and bits which are detachable, have been employed heretofore with but mediocre success due particularly to insufiicient and impractical means for securing the bit to the tool.

The principal object of this invention is m to providea combination tool and bit construction wherein the bit may be firmly secured to the tool and yet be capable of quick detachment.

Another object of importance, is to provide means, whereby the individual cutting elements of a fishtail type bit may be readily replaced.

Other objects and advantages of the invention will become apparent as the same is better understood from the following description and claim.

In the drawings:

Figure 1 represents a fragmentary side elevation of the improved structure. I

Fig. 2 is a fragmentary side elevation looking at the structure from a position at iight angles to the structure as appears in Fig. 3 is a fragmentary longitudinal sectional view through the drilling tool with the bit removed.

Fig. 4 is an end elevation of the bit holdlng end of the tool.

Fig. 5 is a side elevation of one of the bit elements.

Referrin to. the drawings wherein like numerals esignate like parts, the drilhng tool or screw 3 is shown abruptly severed transversely in the manner designated by the 40 numeral 4. The present improved structure 1 is in the nature of a fishtail type of drill and is provided with a pair of detachable bit elements 5-'5, in substitution of the usual cutting blades integral to the tool in conventional drills.

The transversely severed end of the tool 3, is bifurcated, as at 6. Each furcation is provided with an undercut channel 7, and these channels extend longitudinallyof the tool 3 and are slightly tapered inwardly. Each furcation at the bottom of its groove 7 is portion beveled as denoted by the numeral 10, this end portion of the element being also slightly tapered. Each element is also provided with a recess 11 at a point inwardly from said tapered end portion.

The bits are adapted for engagement within the channels in the manner shown in Figs.

1 and 2. The bosses 8 spring into the recess 11 to firmly retain the bit in wedged connection to the tool.

Obviously, in the construction of the novel structure. certain changes may be resorted to without departing from the spirit and scope of the invention as claimed hereinafter.

Having thus described our invention, what we claim as new is In combination, drilling tool provided with a dove-tail groove in the free end thereot', a cutting bit of spring material provided with beveled edges for engagement within the said dove-tailed groove, said spring bit being provided with a recess, and a boss on the bit ,for engagement within the so saidrecess.

In testimony whereof we afiix our signatures. a.

ELZADORE S. MGCULLOUGH.

ASA B. SMITH. s5 

